Unitary light guide plate, light guide plate unit, planar lighting device and liquid crystal display device

Abstract

A unitary light guide plate includes a light exit plane, a thick portion located substantially on a center portion of the light exit plane, thin end portions formed on both sides of the thick portion, a half portion of a parallel groove formed on a backside of the light exit plane to accommodate linearly arranged light sources, inclined back portions arranged so as to become thinner from the thick portion to the thin end portions, and scattering means for scattering light entering from the light sources accommodated in the parallel groove into the thin end portions and propagated through the inclined back portions toward the thick portion. A light guide plate unit has two or more of the unitary light guide plates coupled together in such a way that respective light exit planes are arranged to form a same plane.

Description

TECHNICAL FIELD[0001]The present invention relates to a unitary light guide plate which serves as a transparent light guide plate for diffusing light from a linear light source or a linearly arranged point-like light source in a plane direction to emit a more uniform illumination light from a light exit plane, a light guide plate unit, a planar lighting device using this, a unitary light guide plate for converting incident light from a point-like light source into planar outgoing light, and a planar lighting device and a liquid crystal display device using this.BACKGROUND ART[0002]Conventionally, for a liquid crystal display device, a backlight unit that emits light from a backside of a liquid crystal panel (LCD) to illuminate the liquid crystal panel has been used. The backlight unit is normally configured by using a light source for illumination, a light guide plate for diffusing light emitted from this light source to irradiate the liquid crystal panel with the light, and compone...

AI Technical Summary

Benefits of technology

[0067]According to the first and second embodiments of the first aspect of the present invention, the light guide plate is thin and lightweight, emission efficiency of light from the light exit plane with respect to light emitted from the light source can be increased, and a size of the light exit plane of the light guide plate can be set larger.

[0068]According to the third embodiment of the first aspect of the present invention, by using the unitary light guide plate of the first embodiment and the light guide plate unit of the second embodiment, the thin and lightweight planar lighting device can be manufactured at a lower cost, which enables an increase in emission efficiency of light emitted from the light exit plane with respect to light emitted from the light source, and setting of an illumination surface to a large size, or which can be applied to a liquid crystal display device such as a wall-mounted television.

[0069]According to the light guide plate and the planar lighting device of the first, second and third embodiments of the second aspect of the present invention, light entered from the light entrance plane can reach a farther position in the light guide plate. As a result, a uniform illumination light having no brightness unevenness can be emitted, and thinning, weight-reduction, and enlargement are enabled.

[0070]According to the liquid crystal display device of the third embodiment of the second aspect of the present invention, by installing the planar lighting device to obtain an illumination light of uniform brightness, good displaying can be carried out, and thinning, weight-reduction, and enlargement are enabled.

Problems solved by technology

The backlight unit is expected to become thinner in the future, but it is thought that, in the direct type, the realization of a backlight unit having a thickness of 10 mm or less will be difficult in terms of irregular light-amount.

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